If it hasn't happened to you, count yourself as lucky. For many people, eating ice cream or drinking an icy drink too fast can produce a really painful headache. It usually hits in the front of the brain, behind the forehead.

The technical name for this phenomenon is cold-stimulus headache, but people also refer to it as "ice cream headache" or "brain freeze."

The good news is that brain freeze is easy to prevent — just eat more slowly. The other bit of good news is these headaches don't last very long — a minute at the outside.

Jorge Serrador studies brain freeze headaches, not just because he wants to make the world a safer place for ice cream eaters, but also for what they can tell him about how and why the headaches occur. He's hoping that will lead to better ways to treat or prevent them.

Serrador is the associate director of research at the War Related Illness and Injury Study Center, which is part of the Department of Veterans Affairs in East Orange, N.J. He says many veterans suffer from severe headaches after their deployments.

It turns out it's hard to study headaches, and a brain freeze headache is one of the few types that can be conjured up on demand.

Serrador says no one really knows yet what causes them. But there are some theories. For example, Serrador has shown that just before the brain freeze hits, there's an increase in blood flow to the front of the brain.

"That's increasing the volume and therefore increasing the localized pressure in that area," he says. The brain may be interpreting that increased pressure as pain.

"Another theory that's been put out there is that the cold actually stimulates a nerve in the roof of the mouth," says Serrador. That stimulated nerve in the mouth goes into overdrive. It sends off a barrage of signals to the brain that once again the brain interprets as "ouch."

Why the brain gets "ouch" from the cold and not "brrrrr" is a mystery.

Harvard Medical School headache researcher Elizabeth Loder says it's not all that surprising to think scientists may learn something important from studying ice cream headaches.

"Some of these things that people think of as silly or whimsical, they're actually really fascinating," says Loder, who is also president of the American Headache Society.

Like the enduring mystery of why a sweet treat prompts pain.

This article is part of Joe's Big Idea, an NPR project to explore how innovations come about.

Copyright 2014 NPR. To see more, visit http://www.npr.org/.

Transcript

RENEE MONTAGNE, HOST:

A cool thing to do on a hot summer day is to have an ice cream bar. And I've been up for several hours. It's not that hot yet, but it's plenty hot enough. So, you know, I got myself a box here of chocolate-covered ice cream bars. Think I'll have one right now.

(SOUNDBITE OF OPENING AND CRUNCHING ON ICE CREAM BAR)

MONTAGNE: Umm. Yum.

JOE PALCA, BYLINE: Renee. Renee, hang on.

MONTAGNE: Hi, Joe Palca.

PALCA: Are you aware of the danger you face eating one of those ice creams?

MONTAGNE: Yeah. Right. Gaining weight?

PALCA: No. I mean ice cream headache.

MONTAGNE: A brain freeze?

PALCA: Exactly.

MONTAGNE: Yeah. You know, I've always wondered about brain freeze. I mean, I get them. I get them when I drink a really cold drink really fast out in the heat. But Joe, you're a science correspondent, what generally causes a brain freeze?

PALCA: Well, I'm so glad you asked that because that's the question I'm going to address in this installment of our series Summer Science.

Lucky coincidence.

Yes, isn't it?

MONTAGNE: Mm.

PALCA: Anyway, if we're going to look at this scientifically, we're going to need to be precise about what we mean by brain freeze. So I consulted Jorge Serrador. He's with the Department of Veterans Administration and he studies headaches. He says a brain freeze is what you get when you eat or drink something really cold, really quickly.

DR. JORGE SERRADOR: You get this localized pain, usually sort of in that forehead area.

PALCA: And the pain can be quite intense. But it doesn't last very long. Stop eating or drinking the cold stuff, and the pain goes away in 30 or 40 seconds. And guess what, you remember your mother was always telling you not to wolf down your food. She was right.

SERRADOR: Drink slow, or eat slow, and you probably won't get the associated brain freeze.

MONTAGNE: Joe, but you were going to tell us why you get brain freeze when you eat an ice cream bar, like I am right now, or some cold drink.

PALCA: Exactly. So that's the question I put to Jorge Serrador.

SERRADOR: That is a tough question.

PALCA: Hmm. Helpful. Anyway, it turns out no one really knows for sure, but there are some theories. For example, Serrador has shown that just before the brain freeze hits, there's an increase in blood flow to the front of the brain.

SERRADOR: That's increasing the volume therefore; it's increasing sort of the localized pressure in that area.

PALCA: And the brain may be interpreting that increased pressure as pain.

SERRADOR: Another theory that's been put out there is that the cold actually stimulates a nerve in the roof of the mouth.

PALCA: And that stimulated nerve in the mouth goes into overdrive. It sends off a barrage of signals to the brain that once again the brain interprets as ouch. Although why the brain gets ouch from the cold and not brrr is a bit of a mystery.

Serrador isn't studying brain freeze to help the world become more comfortably when they eat ice cream or drink Slurpees. It turns out it's hard to study headaches, and a brain freeze headache is one of the few you can conjure up on demand. And scientists like Serrador are hoping understanding brain freeze will help them find better treatments for people with chronic headaches or brain injuries.

DR. ELIZABETH LODER: Some of these things that, you know, people think of as sort of silly or whimsical phenomena, they're actually really fascinating.

PALCA: That's Elizabeth Loder. She ought to know. Not only is she a headache researcher at Harvard Medical School, but she's also president of the American Headache Society.

So Renee, how's the ice cream? Did you get a headache?

MONTAGNE: The ice cream's delicious. But, you know, I've been eating it very slowly.

PALCA: Good.

MONTAGNE: And hopefully when I wolf it down right down I won't have a headache.

PALCA: OK.

MONTAGNE: Thank you, Joe.

PALCA: You're welcome.

(SOUNDBITE OF MUSIC)

MONTAGNE: That's NPR's science correspondent Joe Palca.

You can find a video where you can see one of our editors induce brain freeze by eating a Popsicle - all in the name of science. And there's more from our Summer Science series about how to build a campfire or roast the perfect marshmallow, all at our website NPR.org.